I recently decided to build a new virtual server to replace our ageing squid
reverse proxy server. The old one was running Oracle Enterprise Linux 5 with
squid 3.0.STABLE26. I built the new one with Centos 6 and initially I used
the standard version of squid installed with yum, ie 3.1.10. When I had
problems with that I built 3.2.1 but that had the same problem.

The issue is that login=PASS is not working properly with Exchange 2010.
Although normal user logins to OWA work ok, and ActiveSync works ok, the
Soap interface (which is used by the Blackberry Bis server) doesn't
authenticate, and the Exchange server just keeps returning 401 not
authorized.

The rewrite program just redirects http to https and adds /owa onto the end
of the URL if necessary. After turning on some debugging and poring through
log files I saw this request being sent to the Exchange server: